Phthalonitrile can be used in various applications. For example, a composite formed by impregnating a resin (phthalonitrile resin) prepared using phthalonitrile as a monomer into a filler such as glass fiber or carbon fiber can be used as a material for automobiles, airplanes or ships. The process for producing the composite may include, for example, a process of mixing a mixture of phthalonitrile and a curing agent or a prepolymer formed by the reaction of the mixture with a filler and then curing the mixture (see, for example, Patent Document 1). In order for the composite preparation to be effective, it is required that the polymerizable composition or the prepolymer has appropriate fusibility and fluidity and a so-called process window is wide.
The other use of phthalonitrile compounds may include a use as precursors of phthalocyanine dyes. For example, a phthalonitrile compound may be compounded with a metal to be applied as a pigment.
The phthalonitrile compound can be also applied as a precursor of a fluorescent brightener or a photographic sensitizer or a precursor of an acid anhydride, and the like. For example, the phthalonitrile compound can be converted to an acid anhydride via an appropriate oxidation process and dehydration process, and such an acid anhydride can be also used as a precursor of polyamic acid or polyimide, and the like.